Green Peach Aphid

Myzus persicae — the green peach aphid — is THE MOST ECONOMICALLY DAMAGING APHID in the world and one of about 5,000 species in family Aphididae (the aphids — small soft-bodied sap-sucking true bugs). The species is widespread across all temperate and subtropical regions of the world (essentially cosmopolitan — present in essentially every region with intensive agriculture). Adults are 1.7-2.5 mm long, pale yellow-green to pink, with the typical aphid body plan: pear-shaped soft body, long legs, two CORNICLES (small tube-like projections from the rear of the abdomen — distinctive aphid feature), and the species' diagnostic feature: medial ridge between the antennae forming a small horn-like indentation. The species attacks OVER 875 PLANT SPECIES — one of the most polyphagous aphid species and one of the most polyphagous insect herbivores known. Major economic crop hosts include: PEACH (the species' primary winter host — overwintering eggs are laid on peach twigs in autumn, and the spring generations feed on peach leaves before dispersing to summer hosts); MOST VEGETABLES (potato, tomato, pepper, lettuce, spinach, brassicas); MOST FIELD CROPS (sugar beet, cotton, tobacco, sunflower); MOST ORNAMENTALS (roses, chrysanthemums, many others); and many fruit and tree crops. The species' major economic significance comes from VIRUS TRANSMISSION. Green peach aphids are the MOST IMPORTANT VECTOR of plant viral diseases worldwide, transmitting OVER 100 DIFFERENT PLANT VIRUSES — including potato leafroll virus, potato virus Y, beet yellows virus, cucumber mosaic virus, and many other major commercial crop viruses. Plant viruses transmitted by green peach aphids cause more economic damage than the direct feeding damage from the aphids themselves — a single feeding event by a virus-carrying aphid can transmit virus to a previously-healthy plant in seconds. The species reproduces by PARTHENOGENESIS during summer (asexual reproduction — females give birth to live female clones without mating, with each clone able to begin reproducing within 7-10 days of birth). Combined with rapid generation time (one generation per week in warm conditions), parthenogenesis enables EXPLOSIVE POPULATION GROWTH — single aphid colonies can grow from one founder to hundreds of thousands of individuals within a few weeks under favorable conditions. The species can ALTERNATE between asexual summer reproduction (rapid clonal growth on summer hosts) and sexual autumn reproduction (sexual mating with winged males returning to peach tree winter hosts to lay overwintering eggs) — providing both rapid growth and genetic recombination. Annual global agricultural losses to green peach aphid (combining direct feeding damage and transmitted virus damage) are estimated in the BILLIONS OF DOLLARS. The species is the most-studied aphid in modern entomology and the foundational case study in many aspects of insect biology including virus vectoring, parthenogenetic reproduction, host alternation, and insecticide resistance evolution. The species is harmless to humans (no bite, no sting) but is the single most important agricultural pest aphid worldwide.